6Lo Working Group Y-G. Hong
Internet-Draft ETRI
Intended status: Informational C. Gomez
Expires: January 4, 2018 UPC/i2cat
Y-H. Choi
ETRI
D-Y. Ko
SKtelecom
AR. Sangi
Individual Contributor
T. Aanstoot
Modio AB
S. Chakrabarti
July 3, 2017
IPv6 over Constrained Node Networks (6lo) Applicability & Use casesdraft-ietf-6lo-use-cases-02
Abstract
This document describes the applicability of IPv6 over constrained
node networks (6lo) and provides practical deployment examples. In
addition to IEEE 802.15.4, various link layer technologies such as
ITU-T G.9959 (Z-Wave), BLE, DECT-ULE, MS/TP, NFC, PLC (IEEE 1901),
and IEEE 802.15.4e (6tisch) are used as examples. The document
targets an audience who like to understand and evaluate running end-
to-end IPv6 over the constrained link layer networks connecting
devices to each other or to each cloud.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 4, 2018.
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 251. Introduction
Running IPv6 on constrained node networks has different features from
general node networks due to the characteristics of constrained node
networks such as small packet size, short link-layer address, low
bandwidth, network topology, low power, low cost, and large number of
devices [RFC4919][RFC7228]. For example, some IEEE 802.15.4 link
layers have a frame size of 127 octets and IPv6 requires the layer
below to support an MTU of 1280 bytes, therefore an appropriate
fragmentation and reassembly adaptation layer must be provided at the
layer below IPv6. Also, the limited size of IEEE 802.15.4 frame and
low energy consumption requirements make the need for header
compression. The IETF 6LoPWAN (IPv6 over Low powerWPAN) working
group published an adaptation layer for sending IPv6 packets over
IEEE 802.15.4 [RFC4944], a compression format for IPv6 datagrams over
IEEE 802.15.4-based networks [RFC6282], and Neighbor Discovery
Optimization for 6LoPWAN [RFC6775].
As IoT (Internet of Things) services become more popular, IPv6 over
various link layer technologies such as Bluetooth Low Energy
(Bluetooth LE), ITU-T G.9959 (Z-Wave), Digital Enhanced Cordless
Telecommunications - Ultra Low Energy (DECT-ULE), Master-Slave/Token
Passing (MS/TP), Near Field Communication (NFC), Power Line
Communication (PLC), and IEEE 802.15.4e (TSCH), have been defined at
[IETF_6lo] working group. IPv6 stacks for constrained node networks
use a variation of the 6LoWPAN stack applied to each particular link
layer technology.
In the 6LoPWAN working group, the [RFC6568], "Design and Application
Spaces for 6LoWPANs" was published and it describes potential
application scenarios and use cases for low-power wireless personal
area networks. Hence, this 6lo applicability document aims to
provide guidance to an audience who is new to IPv6-over-lowpower
networks concept and wants to assess if variance of 6LoWPAN stack
[6lo] can be applied to the constrained L2 network of their interest.
This 6lo applicability document puts together various design space
dimensions such as deployment, network size, power source,
connectivity, multi-hop communication, traffic pattern, security
level, mobility, and QoS requirements etc. And it described a few
set of 6LoPWAN application scenarios and practical deployment as
examples.
This document provides the applicability and use cases of 6lo,
considering the following aspects:
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o 6lo applicability and use cases MAY be uniquely different from
those of 6LoWPAN defined for IEEE 802.15.4.
o It SHOULD cover various IoT related wire/wireless link layer
technologies providing practical information of such technologies.
o A general guideline on how the 6LoWPAN stack can be modified for a
given L2 technology.
o Example use cases and practical deployment examples.
2. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. 6lo Link layer technologies and possible candidates3.1. ITU-T G.9959 (specified)
The ITU-T G.9959 recommendation [G.9959] targets low-power Personal
Area Networks (PANs). G.9959 defines how a unique 32-bit HomeID
network identifier is assigned by a network controller and how an
8-bit NodeID host identifier is allocated to each node. NodeIDs are
unique within the network identified by the HomeID. The G.9959
HomeID represents an IPv6 subnet that is identified by one or more
IPv6 prefixes [RFC7428]. The ITU-T G.9959 can be used for smart home
applications.
3.2. Bluetooth LE (specified)
Bluetooth LE was introduced in Bluetooth 4.0, enhanced in Bluetooth
4.1, and developed even further in successive versions. Bluetooth
SIG has also published Internet Protocol Support Profile (IPSP). The
IPSP enables discovery of IP-enabled devices and establishment of
link-layer connection for transporting IPv6 packets. IPv6 over
Bluetooth LE is dependent on both Bluetooth 4.1 and IPSP 1.0 or
newer.
Devices such as mobile phones, notebooks, tablets and other handheld
computing devices which will include Bluetooth 4.1 chipsets will
probably also have the low-energy variant of Bluetooth. Bluetooth LE
will also be included in many different types of accessories that
collaborate with mobile devices such as phones, tablets and notebook
computers. An example of a use case for a Bluetooth LE accessory is
a heart rate monitor that sends data via the mobile phone to a server
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on the Internet [RFC7668]. A typical usage of Bluetooth LE is
smartphone-based interaction with constrained devices.
3.3. DECT-ULE (specified)
DECT ULE is a low power air interface technology that is designed to
support both circuit switched services, such as voice communication,
and packet mode data services at modest data rate.
The DECT ULE protocol stack consists of the PHY layer operating at
frequencies in the 1880 - 1920 MHz frequency band depending on the
region and uses a symbol rate of 1.152 Mbps. Radio bearers are
allocated by use of FDMA/TDMA/TDD techniques.
In its generic network topology, DECT is defined as a cellular
network technology. However, the most common configuration is a star
network with a single Fixed Part (FP) defining the network with a
number of Portable Parts (PP) attached. The MAC layer supports
traditional DECT as this is used for services like discovery,
pairing, security features etc. All these features have been reused
from DECT.
The DECT ULE device can switch to the ULE mode of operation,
utilizing the new ULE MAC layer features. The DECT ULE Data Link
Control (DLC) provides multiplexing as well as segmentation and re-
assembly for larger packets from layers above. The DECT ULE layer
also implements per-message authentication and encryption. The DLC
layer ensures packet integrity and preserves packet order, but
delivery is based on best effort.
The current DECT ULE MAC layer standard supports low bandwidth data
broadcast. However the usage of this broadcast service has not yet
been standardized for higher layers [RFC8105]. DECT-ULE can be used
for smart metering in a home.
3.4. MS/TP (specified)
MS/TP is a contention-free access method for the RS-485 physical
layer, which is used extensively in building automation networks.
An MS/TP device is typically based on a low-cost microcontroller with
limited processing power and memory. Together with low data rates
and a small address space, these constraints are similar to those
faced in 6lowpan networks and suggest some elements of that solution
might be leveraged. MS/TP differs significantly from 6lowpan in at
least three aspects: a) MS/TP devices typically have a continuous
source of power, b) all MS/TP devices on a segment can communicate
directly so there are no hidden node or mesh routing issues, and c)
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recent changes to MS/TP provide support for large payloads,
eliminating the need for link-layer fragmentation and reassembly.
MS/TP is designed to enable multidrop networks over shielded twisted
pair wiring, although not according to standards, in lower speeds,
normally 9600 bit/s, re-purposed telecom wiring is widely in use,
keeping deployment cost down. It can support a data rate of 115,200
baud on segments up to 1000 meters in length, or segments up to 1200
meters in length at lower baud rates. An MS/TP link requires only a
UART, an RS-485 transceiver with a driver that can be disabled, and a
5ms resolution timer. These features make MS/TP a cost-effective and
very reliable field bus for the most numerous and least expensive
devices in a building automation network [RFC8163]. MS/TP can be
used for the management of district heating.
3.5. NFC (specified)
NFC technology enables simple and safe two-way interactions between
electronic devices, allowing consumers to perform contactless
transactions, access digital content, and connect electronic devices
with a single touch. NFC complements many popular consumer level
wireless technologies, by utilizing the key elements in existing
standards for contactless card technology (ISO/IEC 14443 A&B and
JIS-X 6319-4). NFC can be compatible with existing contactless card
infrastructure and it enables a consumer to utilize one device across
different systems.
Extending the capability of contactless card technology, NFC also
enables devices to share information at a distance that is less than
10 cm with a maximum communication speed of 424 kbps. Users can
share business cards, make transactions, access information from a
smart poster or provide credentials for access control systems with a
simple touch.
NFC's bidirectional communication ability is ideal for establishing
connections with other technologies by the simplicity of touch. In
addition to the easy connection and quick transactions, simple data
sharing is also available [I-D.ietf-6lo-nfc]. NFC can be used for
secure transfer in healthcare services.
3.6. PLC (specified)
Unlike other dedicated communication infrastructure, the required
medium (power conductor) is widely available indoors and outdoors.
Moreover, wired technologies are more susceptible to cause
interference but are more reliable than their wireless counterparts.
PLC is a data transmission technique that utilizes power conductors
as medium.
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The below table shows some available open standards defining PLC.
+-------------+-----------------+------------+-----------+----------+
| PLC Systems | Frequency Range | Type | Data Rate | Distance |
+-------------+-----------------+------------+-----------+----------+
| IEEE1901 | <100MHz | Broadband | 200Mbps | 1000m |
| | | | | |
| IEEE1901.1 | <15MHz | PLC-IoT | 10Mbps | 2000m |
| | | | | |
| IEEE1901.2 | <500kHz | Narrowband | 200Kbps | 3000m |
+-------------+-----------------+------------+-----------+----------+
Table 1: Some Available Open Standards in PLC
[IEEE1901] defines broadband variant of PLC but is effective within
short range. This standard addresses the requirements of
applications with high data rate such as: Internet, HDTV, Audio,
Gaming etc. Broadband operates on OFDM (Orthogonal Frequency
Division Multiplexing) modulation.
[IEEE1901.2] defines narrowband variant of PLC with less data rate
but significantly higher transmission range that could be used in an
indoor or even an outdoor environment. It is applicable to typical
IoT applications such as: Building Automation, Renewable Energy,
Advanced Metering, Street Lighting, Electric Vehicle, Smart Grid etc.
Moreover, IEEE 1901.2 standard is based on the 802.15.4 MAC sub-layer
and fully endorses the security scheme defined in 802.15.4.
[RFC8036]. A typical use case of PLC is smart grid.
3.7. IEEE 802.15.4e (specified)
The Time Slotted Channel Hopping (TSCH) mode was introduced in the
IEEE 802.15.4-2015 standard. In a TSCH network, all nodes are
synchronized. Time is sliced up into timeslots. The duration of a
timeslot, typically 10ms, is large enough for a node to send a full-
sized frame to its neighbor, and for that neighbor to send back an
acknowledgment to indicate successful reception. Timeslots are
grouped into one of more slotframes, which repeat over time.
All the communication in the network is orchestrated by a
communication schedule which indicates to each node what to do in
each of the timeslots of a slotframe: transmit, listen or sleep. The
communication schedule can be built so that the right amount of link-
layer resources (the cells in the schedule) are scheduled to satisfy
the communication needs of the applications running on the network,
while keeping the energy consumption of the nodes very low. Cells
can be scheduled in a collision-free way, introducing a high level of
determinism to the network.
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A TSCH network exploits channel hopping: subsequent packet exchanges
between neighbor nodes are done on a different frequency. This means
that, if a frame isn't received, the transmitter node will re-
transmitt the frame on a different frequency. The resulting "channel
hopping" efficiently combats external interference and multi-path
fading.
The main benefits of IEEE 802.15.4 TSCH are:
- ultra high reliability. Off-the-shelf commercial products offer
over 99.999% end-to-end reliability.
- ultra low-power consumption. Off-the-shelf commercial products
offer over a decade of battery lifetime.
- 6TiSCH at IETF defines communications of TSCH network and it
uses 6LoWPAN stack [RFC7554].
IEEE 802.15.4e can be used for industrial automation.
3.8. LTE MTC (example of a potential candidate)
LTE category defines the overall performance and capabilities of the
UE(User Equipment). For example, the maximum down rate of category 1
UE and category 2 UE are 10.3 Mbit/s and 51.0 Mbit/s respectively.
There are many categories in LTE standard. 3GPP standards defined the
category 0 to be used for low rate IoT service in release 12. Since
category 1 and category 0 could be used for low rate IoT service,
these categories are called LTE MTC (Machine Type Communication)
[LTE_MTC].
LTE MTC offer advantages in comparison to above category 2 and is
appropriate to be used for low rate IoT services such as low power
and low cost. LTE MTC can be used for a gateway of a wireless
bachhaul network.
3.9. Comparison between 6lo Link layer technologies
In above clauses, various 6lo Link layer technologies and a possible
candidate are described. The following table shows that dominant
paramters of each use case corresponding to the 6lo link layer
technology.
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o Address assignment and network configuration are specified using
DHCPv6 [RFC3315]. Neighbor Discovery (ND) [RFC6775] and stateless
address auto-configuration (SLAAC) are not supported.
o The network layer consists of IPv6, ICPMv6 and 6lo/6LoPWAN header
compression [RFC6282]. Multicast is supported using MPL. Two
domains are supported, a delay sensitive MPL domain for low
latency applications (e.g. DSM, DSR) and a delay insensitive one
for less stringent applications (e.g. OTA file transfers).
o The routing layer uses RPL [RFC6550] in non-storing mode with the
MRHOF objective function based on the ETX metric.
4.2. Wi-SUN usage of 6lo stacks
Wireless Smart Ubiquitous Network (Wi-SUN) is a technology based on
the IEEE 802.15.4g standard. Wi-SUN networks support star and mesh
topologies, as well as hybrid star/mesh deployments, but are
typically laid out in a mesh topology where each node relays data for
the network to provide network connectivity. Wi-SUN networks are
deployed on both powered and battery-operated devices.
The main application domains targeted by Wi-SUN are smart utility and
smart city networks. This includes, but is not limited to the
following applications:
o Advanced Metering
o Infrastructure (AMI)
o Distribution Automation
o Home Energy Management
o Infrastructure Management
o Intelligent Transportation Systems
o Smart Street Lighting
o Agriculture
o Structural health (bridges, buildings etc)
o Monitoring and Asset Management
o Smart Thermostats, Air Conditioning and Heat Controls
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o Energy Usage Information Displays
The Wi-SUN Alliance Field Area Network (FAN) covers primarily outdoor
networks, and its specification is oriented towards meeting the more
rigorous challenges of these environments. Examples include from
meter to outdoor access point/router for AMI and DR, or between
switches for DA. However, nothing in the profile restricts it to
outdoor use. It has the following features;
o Open standards based on IEEE802, IETF, TIA, ETSI
o Architecture is an IPv6 frequency hopping wireless mesh network
with enterprise level security
o Simple infrastructure which is low cost, low complexity
o Enhanced network robustness, reliability, and resilience to
interference, due to high redundancy and frequency hopping
o Enhaced scalability, long range, and energy friendliness
o Supports multiple global license-exempt sub GHz bands
o Multi-vendor interoperability
o Very low power modes in development permitting long term battery
operation of network nodes
In the Wi-SUN FAN specification, adaptation layer based on 6lo and
IPv6 network layer are described. So, IPv6 protocol suite including
TCP/UDP, 6lo Adaptation, Header Compression, DHCPv6 for IP address
management, Routing using RPL, ICMPv6, and Unicast/Multicast
forwarding is utilized.
5. Design Space and Guidelines for 6lo Deployment5.1. Design Space Dimensions for 6lo Deployment
The [RFC6568] lists the dimensions used to describe the design space
of wireless sensor networks in the context of the 6LoWPAN working
group. The design space is already limited by the unique
characteristics of a LoWPAN (e.g., low power, short range, low bit
rate). In [RFC6568], the following design space dimensions are
described; Deployment, Network size, Power source, Connectivity,
Multi-hop communication, Traffic pattern, Mobility, Quality of
Service (QoS). However, in this document, the following design space
dimensions are considered:
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o Deployment/Bootstrapping: 6lo nodes can be connected randomly, or
in an organized manner. The bootstrapping has different
characteristics for each link layer technology.
o Topology: Topology of 6lo networks may inherently follow the
characteristics of each link layer technology. Point-to-point,
star, tree or mesh topologies can be configured, depending on the
link layer technology considered.
o L2-Mesh or L3-Mesh: L2-mesh and L3-mesh may inherently follow the
characteristics of each link layer technology. Some link layer
technologies may support L2-mesh and some may not support.
o Multi-link subnet, single subnet: The selection of multi-link
subnet and single subnet depends on connectivity and the number of
6lo nodes.
o Data rate: Originally, the link layer technologies of 6lo have low
rate of data transmission. But, by adjusting the MTU, it can
deliver higher data rate.
o Buffering requirements: Some 6lo use case may require more data
rate than the link layer technology support. In this case, a
buffering mechanism to manage the data is required.
o Security and Privacy Requirements: Some 6lo use case can involve
transferring some important and personal data between 6lo nodes.
In this case, high-level security support is required.
o Mobility across 6lo networks and subnets: The movement of 6lo
nodes is dependent on the 6lo use case. If the 6lo nodes can move
or moved around, it requires a mobility management mechanism.
o Time synchronization requirements: The requirement of time
synchronization of the upper layer service is dependent on the 6lo
use case. For some 6lo use case related to health service, the
measured data must be recorded with exact time and must be
transferred with time synchronization.
o Reliability and QoS: Some 6lo use case requires high reliability,
for example real-time service or health-related services.
o Traffic patterns: 6lo use cases may involve various traffic
patterns. For example, some 6lo use case may require short data
length and random transmission. Some 6lo use case may require
continuous data and periodic data transmission.
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o Security Bootstrapping: Without the external operations, 6lo nodes
must have the security bootstrapping mechanism.
o Power use strategy: to enable certain use cases, there may be
requirements on the class of energy availability and the strategy
followed for using power for communication [RFC7228]. Each link
layer technology defines a particular power use strategy which may
be tuned [I-D.ietf-lwig-energy-efficient]. Readers are expected
to be familiar with [RFC7228] terminology.
o Update firmware requirements: Most 6lo use cases will need a
mechanism for updating firmware. In these cases support for over
the air updates are required, probably in a broadcast mode when
bandwith is low and the number of identical devices is high.
5.2. Guidelines for adopting IPv6 stack (6lo/6LoWPAN)
The following guideline targets candidates for new constrained L2
technologies that consider running modified 6LoWPAN stack. The
modification of 6LoWPAN stack should be based on the following:
o Addressing Model: Addressing model determines whether the device
is capable of forming IPv6 Link-local and global addresses and
what is the best way to derive the IPv6 addresses for the
constrained L2 devices. Whether the device is capable of forming
IPv6 Link-local and global addresses, L2-address-derived IPv6
addresses are specified in [RFC4944], but there exist implications
for privacy. For global usage, a unique IPv6 address must be
derived using an assigned prefix and a unique interface ID.
[RFC8065] provides such guidelines. For MAC derived IPv6 address,
please refer to [RFC8163] for IPv6 address mapping examples.
Broadcast and multicast support are dependent on the L2 networks.
Most lowpower L2 implementations map multicast to broadcast
networks. So care must be taken in the design when to use
broadcast and try to stick to unicast messaging whenever possible.
o MTU Considerations: The deployment SHOULD consider their need for
maximum transmission unit of a packet (MTU) over the link layer
and should consider if fragmentation and reassembly of packets are
needed at the 6LoWPAN layer. For example, if the link-layer
supports fragmentation and reassembly of packets, then 6LoWPAN
layer may skip supporting fragmentation/reassembly. In fact, for
most efficiency, choosing a low-power link-layer that can carry
unfragmented application packets would be optimum for packet
transmission if the deployment can afford it. Please refer to 6lo
RFCs [RFC7668], [RFC8163], [RFC8105] for example guidance.
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o Mesh or L3-Routing: 6LoWPAN specifications do provide mechanisms
to support for mesh routing at L2. [RFC6550] defines L3 routing
for low power lossy networks using directed graphs. 6LoWPAN is
routing protocol agnostic and other L2 or L3 routing protocols can
be run using a 6LoWPAN stack.
o Address Assignment: 6LoWPAN requires that IPv6 Neighbor Discovery
for low power networks [RFC6775] be used for autoconfiguration of
stateless IPv6 address assignment. Considering the energy
sensitive networks [RFC6775] makes optimization from classical
IPv6 ND [RFC4861] protocol. It is the responsibility of the
deployment to ensure unique global IPv6 addresses for the Internet
connectivity. For local-only connectivity IPv6 ULA may be used.
[RFC6775] specifies the 6LoWPAN border router(6LBR) which is
responsible for prefix assignment to the 6lo/6LoWPAN network. 6LBR
can be connected to the Internet or Enterprise network via its one
of the interfaces. Please refer to [RFC7668] and [RFC8105] for
examples of address assignment considerations. In addition,
privacy considerations [RFC8065] must be consulted for
applicability. In certain scenarios, the deployment may not
support autoconfiguration of IPv6 addressing due to regulatory and
business reasons and may choose to offer a separate address
assignment service.
o Header Compression: IPv6 header compression [RFC6282] is a vital
part of IPv6 over low power communication. Examples of header
compression for different link-layers specifications are found in
[RFC7668], [RFC8163], [RFC8105]. A generic header compression
technique is specified in [RFC7400].
o Security and Encryption: Though 6LoWPAN basic specifications do
not address security at network layer, the assumption is that L2
security must be present. In addition, application level security
is highly desirable. The working groups [ace] and [core] should
be consulted for application and transport level security. 6lo
working group is working on address authentication [6lo-ap-nd] and
secure bootstrapping is also being discussed at IETF. However,
there may be different levels of security available in a
deployment through other standards such as hardware level security
or certificates for initial booting process. Encryption is quite
important if the implementation can afford it.
o Additional processing: [RFC8066] defines guidelines for ESC
dispatch octets use in the 6LoWPAN header. An implementation may
take advantage of ESC header to offer a deployment specific
processing of 6LoWPAN packets.
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As IPv6 stacks for constrained node networks use a variation of the
6LoWPAN stack applied to each particular link layer technology,
various 6lo use cases can be provided. In this clause, one 6lo use
case example of Bluetooth LE (Smartphone-Based Interaction with
Constrained Devices) is described. Other 6lo use case examples are
described in Appendix.
The key feature behind the current high Bluetooth LE momentum is its
support in a large majority of smartphones in the market. Bluetooth
LE can be used to allow the interaction between the smartphone and
surrounding sensors or actuators. Furthermore, Bluetooth LE is also
the main radio interface currently available in wearables. Since a
smartphone typically has several radio interfaces that provide
Internet access, such as Wi-Fi or 4G, the smartphone can act as a
gateway for nearby devices such as sensors, actuators or wearables.
Bluetooth LE may be used in several domains, including healthcare,
sports/wellness and home automation.
Example: Use of Bluetooth LE-based Body Area Network for fitness
A person wears a smartwatch for fitness purposes. The smartwatch has
several sensors (e.g. heart rate, accelerometer, gyrometer, GPS,
temperature, etc.), a display, and a Bluetooth LE radio interface.
The smartwatch can show fitness-related statistics on its display.
However, when a paired smartphone is in the range of the smartwatch,
the latter can report almost real-time measurements of its sensors to
the smartphone, which can forward the data to a cloud service on the
Internet. In addition, the smartwatch can receive notifications
(e.g. alarm signals) from the cloud service via the smartphone. On
the other hand, the smartphone may locally generate messages for the
smartwatch, such as e-mail reception or calendar notifications.
The functionality supported by the smartwatch may be complemented by
other devices such as other on-body sensors, wireless headsets or
head-mounted displays. All such devices may connect to the
smartphone creating a star topology network whereby the smartphone is
the central component.
7. IANA Considerations
There are no IANA considerations related to this document.
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Security considerations are not directly applicable to this document.
The use cases will use the security requirements described in the
protocol specifications.
9. Acknowledgements
Carles Gomez has been funded in part by the Spanish Government
(Ministerio de Educacion, Cultura y Deporte) through the Jose
Castillejo grant CAS15/00336. His contribution to this work has been
carried out in part during his stay as a visiting scholar at the
Computer Laboratory of the University of Cambridge.
Thomas Watteyne, Pascal Thubert, Xavier Vilajosana, Daniel Migault,
and Jianqiang HOU have provided valuable feedback for this draft.
Das Subir and Michel Veillette have provided valuable information of
jupiterMesh and Paul Duffy has provided valuable information of Wi-
SUN for this draft.
10. References10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007,
<http://www.rfc-editor.org/info/rfc4919>.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<http://www.rfc-editor.org/info/rfc4944>.
[RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation
Routing Requirements in Low-Power and Lossy Networks",
RFC 5826, DOI 10.17487/RFC5826, April 2010,
<http://www.rfc-editor.org/info/rfc5826>.
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[IEEE1901]
"IEEE Standard, IEEE Std. 1901-2010 - IEEE Standard for
Broadband over Power Line Networks: Medium Access Control
and Physical Layer Specifications", 2010,
<https://standards.ieee.org/findstds/standard/1901-2010.html>.
[IEEE1901.1]
"IEEE Standard (work-in-progress), IEEE-SA Standards
Board", <http://sites.ieee.org/sagroups-1901-1/>.
[IEEE1901.2]
"IEEE Standard, IEEE Std. 1901.2-2013 - IEEE Standard for
Low-Frequency (less than 500 kHz) Narrowband Power Line
Communications for Smart Grid Applications", 2013,
<https://standards.ieee.org/findstds/standard/1901.2-2013.html>.
Appendix A. Other 6lo Use Case ExamplesA.1. Use case of ITU-T G.9959: Smart Home
Z-Wave is one of the main technologies that may be used to enable
smart home applications. Born as a proprietary technology, Z-Wave
was specifically designed for this particular use case. Recently,
the Z-Wave radio interface (physical and MAC layers) has been
standardized as the ITU-T G.9959 specification.
Example: Use of ITU-T G.9959 for Home Automation
Variety of home devices (e.g. light dimmers/switches, plugs,
thermostats, blinds/curtains and remote controls) are augmented with
ITU-T G.9959 interfaces. A user may turn on/off or may control home
appliances by pressing a wall switch or by pressing a button in a
remote control. Scenes may be programmed, so that after a given
event, the home devices adopt a specific configuration. Sensors may
also periodically send measurements of several parameters (e.g. gas
presence, light, temperature, humidity, etc.) which are collected at
a sink device, or may generate commands for actuators (e.g. a smoke
sensor may send an alarm message to a safety system).
The devices involved in the described scenario are nodes of a network
that follows the mesh topology, which is suitable for path diversity
to face indoor multipath propagation issues. The multihop paradigm
allows end-to-end connectivity when direct range communication is not
possible. Security support is required, specially for safety-related
communication. When a user interaction (e.g. a button press)
triggers a message that encapsulates a command, if the message is
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lost, the user may have to perform further interactions to achieve
the desired effect (e.g. a light is turned off). A reaction to a
user interaction will be perceived by the user as immediate as long
as the reaction takes place within 0.5 seconds [RFC5826].
A.2. Use case of DECT-ULE: Smart Home
DECT is a technology widely used for wireless telephone
communications in residential scenarios. Since DECT-ULE is a low-
power variant of DECT, DECT-ULE can be used to connect constrained
devices such as sensors and actuators to a Fixed Part, a device that
typically acts as a base station for wireless telephones. Therefore,
DECT-ULE is specially suitable for the connected home space in
application areas such as home automation, smart metering, safety,
healthcare, etc.
Example: Use of DECT-ULE for Smart Metering
The smart electricity meter of a home is equipped with a DECT-ULE
transceiver. This device is in the coverage range of the Fixed Part
of the home. The Fixed Part can act as a router connected to the
Internet. This way, the smart meter can transmit electricity
consumption readings through the DECT-ULE link with the Fixed Part,
and the latter can forward such readings to the utility company using
Wide Area Network (WAN) links. The meter can also receive queries
from the utility company or from an advanced energy control system
controlled by the user, which may also be connected to the Fixed Part
via DECT-ULE.
A.3. Use case of MS/TP: Management of District Heating
The key feature of MS/TP is it's ability to run on the same cabling
as BACnet and some use of ModBus, the defacto standard for low
bandwith industry communication. Specially Modbus has been around
since the 1980 and is still the standard for talking to fans, heat
pumps, water purifying equipment and everything else delivering
electricity, clean water and ventilation.
Example: Use of MS/TP for management of district heating
The mechanical room in the cellar of an apartment building gets
district heating and electricity from the utility providers. The
room has a Supervisory Control And Data Acquisition (SCADA) computer
talking to a centralized server and command center somewhere else
over IP, on the other hand it is controlling the heating, fans and
distribution panel over a 2-wire RS-485 based protocol to make sure
the logic controller for district heating keeps a constant
temperature at the tapwater, the logic controller for heat produktion
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keeps the right radiator temperature depending on the weather and the
fans have a correct speed and are switched off in case district
heating fails to prevent cooling out the building and give certain
commands in case smoke is detected. Speed is not important, in this
usecase, 19,200 bit/s capable equipment is sold as high speed
communication capable. Reliability is important, this not working
will easily give millions of dollars of damage. Normally the setup
is that the SCADA device asks a question to a specific controlling
device, gets an answer from the controlling device, asks a new
question to some other device.
A.4. Use case of NFC: Alternative Secure Transfer
According to applications, various secured data can be handled and
transferred. Depending on security level of the data, methods for
transfer can be alternatively selected.
Example: Use of NFC for Secure Transfer in Healthcare Services with
Tele-Assistance
A senior citizen who lives alone wears one to several wearable 6lo
devices to measure heartbeat, pulse rate, etc. The 6lo devices are
densely installed at home for movement detection. An LoWPAN Border
Router (LBR) at home will send the sensed information to a connected
healthcare center. Portable base stations with LCDs may be used to
check the data at home, as well. Data is gathered in both periodic
and event-driven fashion. In this application, event-driven data can
be very time-critical. In addition, privacy also becomes a serious
issue in this case, as the sensed data is very personal.
While the senior citizen is provided audio and video healthcare
services by a tele-assistance based on LTE connections, the senior
citizen can alternatively use NFC connections to transfer the
personal sensed data to the tele-assistance. At this moment, hidden
hackers can overhear the data based on the LTE connection, but they
cannot gather the personal data over the NFC connection.
A.5. Use case of PLC: Smart Grid
Smart grid concept is based on numerous operational and energy
measuring sub-systems of an electric grid. It comprises of multiple
administrative levels/segments to provide connectivity among these
numerous components. Last mile connectivity is established over LV
segment, whereas connectivity over electricity distribution takes
place in HV segment.
Although other wired and wireless technologies are also used in Smart
Grid (Advance Metering Infrastructure - AMI, Demand Response - DR,
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Home Energy Management System - HEMS, Wide Area Situational Awareness
- WASA etc), PLC enjoys the advantage of existing (power conductor)
medium and better reliable data communication. PLC is a promising
wired communication technology in that the electrical power lines are
already there and the deployment cost can be comparable to wireless
technologies. The 6lo related scenarios lie in the low voltage PLC
networks with most applications in the area of Advanced Metering
Infrastructure, Vehicle-to-Grid communications, in-home energy
management and smart street lighting.
Example: Use of PLC for Advanced Metering Infrastructure
Household electricity meters transmit time-based data of electric
power consumption through PLC. Data concentrators receive all the
meter data in their corresponding living districts and send them to
the Meter Data Management System (MDMS) through WAN network (e.g.
Medium-Voltage PLC, Ethernet or GPRS) for storage and analysis. Two-
way communications are enabled which means smart meters can do
actions like notification of electricity charges according to the
commands from the utility company.
With the existing power line infrastructure as communication medium,
cost on building up the PLC network is naturally saved, and more
importantly, labor operational costs can be minimized from a long-
term perspective. Furthermore, this AMI application speeds up
electricity charge, reduces losses by restraining power theft and
helps to manage the health of the grid based on line loss analysis.
Example: Use of PLC (IEEE1901.1) for WASA in Smart Grid
Many sub-systems of Smart Grid require low data rate and narrowband
variant (IEEE1901.2) of PLC fulfils such requirements. Recently,
more complex scenarios are emerging that require higher data rates.
WASA sub-system is an appropriate example that collects large amount
of information about the current state of the grid over wide area
from electric substations as well as power transmission lines. The
collected feedback is used for monitoring, controlling and protecting
all the sub-systems.
A.6. Use case of IEEE 802.15.4e: Industrial Automation
Typical scenario of Industrial Automation where sensor and actuators
are connected through the time-slotted radio access (IEEE 802.15.4e).
For that, there will be a point-to-point control signal exchange in
between sensors and actuators to trigger the critical control
information. In such scenarios, point-to-point traffic flows are
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